The present invention relates to a hard disk drive, and more specifically to a shielding structure of a hard disk drive.
A hard disk drive is generally used within a computer, wherein electromagnetic noise is abundant.
Therefore, it is required that a hard disk drive be of a structure that is resistant to outside electromagnetic noise.
FIGS. 1 and 2 show a conventional hard disk 10.
The hard disk drive 10 is configured such that to a die-cast aluminum base 14 fitted with a hard disk 12, an actuator 13, and other parts, an die-cast aluminum cover 16 is fixed by means of screws 17, with a gasket 15 sandwiched between the cover 16 and the base 14.
The gasket 15, made of foam resin, is an insulator.
In threaded corner portions of the base 14 and corresponding portions of the cover 16 are formed flat surface portions 18.sub.-1 - 18.sub.-4 and 19.sub.-1 - 19.sub.-4 respectively.
The cover 16 is fixed in such a way that the flat surface portions 18.sub.-1 - 18.sub.-4 are in contact with the corresponding flat surface portions 19.sub.-1 - 19.sub.-4.
The base 14 is grounded.
The base 14, the cover 16, the gasket 15, and the screws 17 constitute a shielding structure.
From a viewpoint of preventing invasion of electromagnetic noise, the shielding structure of the hard disk drive 10 includes slit windows 20, 21, 22, and having a width of W and a length of L.sub.1 or L.sub.2, as shown in FIGS. 2 and 3.
As regards a slit window in general, the maximum length of the straight portion determines the amount of electromagnetic noise invasion; the longer the straight portion, the larger the amount of electromagnetic noise invasion.
Accordingly, with the above construction, there is a potential that, of the windows 20, 21, 22, and 23, the slit windows 20 and 22, which are larger than the other two, present a problem.
As shown in FIG. 4 in an exaggerated manner, with the above construction, one-sided contact (i.e. contact not on the entire flat surfaces 18 and 19) could be created between the flat surface portion 18.sub.-1 and the flat surface portion 19.sub.-1, and also between the flat surface portion 18.sub.-2 and the flat surface portion 19.sub.-2.
One possible result of this incomplete contact is that a slit window 20A of a length L.sub.2, longer than the normal length L.sub.1 could be created, thus causing the set to be more susceptible to electromagnetic noise invasion.
Another possible result is that electric contact between the cover 16 and the base 14 could be insufficient.
For these two reasons, the shielding structure of the conventional hard disk drive 10 has a disadvantage in that it has a potential of not working to the fullest of its electromagnetic noise invasion prevention capability, thereby lacking in reliability.